The present invention generally relates to apparatus for opening bags, particularly to apparatus for opening bags for food products, more particularly to apparatus for opening bags having gusseted sides, and specifically to apparatus for opening microwave popcorn bags.
Popcorn is a highly popular snack food item. In the past, the at-home preparation of popcorn by the consumer involved adding kernel popcorn plus a cooking oil to a covered pot and heating until the popcorn kernels popped to make popcorn. As used herein, "kernel popcorn" refers to unpopped popcorn. The noun "popcorn" or synonymously "popped popcorn" refers herein to popped kernel popcorn. The adjective "popcorn" can refer to either.
More recently, microwave popcorn products have become extremely popular. At present, in the United States of America, over 70 different brands of microwave popcorn products are available. In general, the more popular microwave popcorn products comprise an expandable paper bag containing a charge of kernel popcorn, fat and salt. The microwave popcorn article is adapted to be heated in a microwave oven for three to five minutes to produce the popped popcorn. More recently, improved microwave popcorn articles have been fabricated employing a metallized susceptor which facilitates the heating of the popcorn-fat charge and which, in turn, leads desirably to increases in popcorn volume and decreases in unpopped kernels. Microwave popcorn articles of this type are described in detail in, for example, U.S. Pat. No. 4,450,180 (issued May 22, 1984 to J. D. Watkins and incorporated herein by reference).
The prior art is replete with various apparatus and methods for filling and sealing microwave popcorn bags and in some cases folding the bag generally into a central portion having first and second wing portions extending from opposite ends thereof from folds. For example, U.S. Pat. Nos. 4,450,180; 4,548,826; 4,604,854; and 5,171,950 show techniques for filling and sealing microwave popcorn bags. Particularly, the charge of popcorn, fat and salt could be dropped as a prefabricated toroid- or doughnut-shaped piece into an open end of the bag prior to its sealing. More recently, the popcorn, fat in the form of a slurry, and salt are filled in the open end of the bag prior to its sealing. However, changes in the marketing of microwave popcorn have created demand for improved techniques for opening microwave popcorn bags. Specifically, with the increasing competitiveness of the microwave popcorn business, a need exists for apparatus and methods which achieve higher output speeds in "bags per minute" while reducing the amount of labor, downtime, and floor space required. Additionally, with the reduction in the amount of material and/or layers utilized in the formation of paper popcorn packages including a microwave susceptor such as shown and described in International Publication No. WO 93/15976 published on Aug. 19, 1993, a need exists for apparatus and methods which are capable of running bags of flimsy construction as well as reducing product and material damage. Additionally, with the introduction of various types and sizes of bags to meet particular market types and conditions and for enhancing product performance, a need exists for apparatus and methods which are capable of handling different sizes of bags such as single or multiple serving sizes, and/or different types such as gusseted or non-gusseted bags, and/or different configurations of bags.